AMBER Archive (2007)

Subject: AMBER: ptraj hbond mask

From: Lars Skjærven (lars.skjarven_at_biomed.uib.no)
Date: Mon Nov 05 2007 - 10:00:03 CST


Dear Amber user,

I am trying to calculate the hydrogen bonds between two monomers in a
complex. Due to the fact that hbond calculations are rather computationally
expensive (in terms of memory) I can only do this in the interface between
the two monomers. Hence, I need masks that specifies these areas in the two
monomers. I have used the ptraj script for calculating hbonds found here:
http://amber.scripps.edu/tutorials/basic/tutorial3/section6.htm. However,
this will calculate all the hbonds in the complex and is by far too memory
expensive for my complex.

So my question is: How can I write masks for finding hbonds between two
monomers ? Or actually, between parts of two monomers..

My suggestion was first to change
acceptor mask :LYS_at_NZ :LYS_at_HZ1
to
acceptor mask :1-134,410-524_at_LYS@NZ :1-134,410-524_at_LYS@HZ1

to define the acceptors to be only in this area. Then the donors are defined
to be in:
donor mask :2000-2400,3150-3270_at_GLN@OE1

I would do this for every potential donor/acceptor atoms. This method yields
alot of warnings like:
"WARNING in ptraj, acceptor: There is not a 1-1 correspondence between the"
so I suspect my masks are not that clever after all.. :-)

I tried to use the same masks in "ambmask" to check the masks, but I realise
the syntax used in ptraj and ambmask are not the same? I also checked to
find more documentation on this, but without any luck..

Thanks for any help :-)

Best regards,
Lars Skjaerven

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